Being in my second year of college, I’ve come to accept my abnormal sleep habits at school. I get, on average, six hours of sleep per night, sleep for 10-12 hours on the weekend to “catch up”, and then the cycle starts all over again. But I have started to realize that I pretty much always feel tired, no matter how much sleep I get, so I began to wonder—can we actually catch up on lost sleep, or once we lose those hours are they gone forever?
Lack of sleep is a really common problem, especially among college students, and it leads to many negative consequences including weight gain, diabetes, heart disease, general moodiness—even mood disorders such as anxiety and depression, a weakened immune system, and an overall lowered life expectancy. These health effects are well-researched and well-known, but sometimes it’s just impossible to squeeze in those needed hours of sleep between studying for that test, working, and doing whatever else we need to do. So it would be helpful to know if the lack of sleep during the week can be made up during those blissful weekend days.
I first looked at this article, published in 2016 in the Diabetes Care Journal. They conducted a study to determine if the effects of lack of sleep on diabetes risk could be reversed by increasing the amount of sleep one gets for just a couple nights. In the study, nineteen healthy young men were allowed four nights of normal sleep—8.5 hours in bed—and four nights of restricted sleep—4.5 hours in bed. The two nights following the four nights of only 4.5 hours of sleep were designated recovery nights; the men were allowed 12 hours of sleep on the first recovery night and 10 hours of sleep on the second recovery night. After each phase of the study—normal sleep, sleep deprivation, and recovery sleep—the men’s insulin sensitivity—how our body regulates blood sugar— and response to glucose was measured.
Insulin sensitivity was found to decrease by 23% after the nights of just 4.5 hours of sleep, but the sensitivity was improved after the nights of recovery sleep. The insulin response to glucose, however, did not change according to the amount of sleep one received. The disposition index, which is insulin sensitivity multiplied by the insulin response to glucose, decreased by 16% after sleep deprived nights relative to the nights of 8.5 hours of sleep. This amount of decrease is a predictor of increased diabetes risk. The disposition index, however, went back to normal after the two nights of recovery sleep. This shows that just two nights of increased sleep following four nights of sleep deprivation is enough to reset the body’s insulin sensitivity and reactivity and therefore save the body from being at an increased risk for diabetes.
This study was well conducted; meals were standardized, the subjects were under controlled experimental conditions, and the type of men studied were relatively similar in their age and health, which eliminated confounding variables such as the influence that one’s bed has on sleep, the effect of diet on sleep, the effect of age on the ability to recover from sleep loss etc. But the study was very small with just 19 subjects studied and the subjects were only men, so the results cannot be generalized to females. The study also only looked at a short period of sleep deprivation, and in the case of many people, especially college students, we are more sleep deprived than just four nights of lacking sleep.
Also, this study only looked at how lack of sleep and recovery sleep affects diabetes risk, which is a concern, but not as applicable to college students as say, how sleep affects school performance. So, although this doesn’t conclude that a weekend of extra sleep allows us to reverse the accumulated sleep debt of the week, it does give us hope that getting those extra hours of sleep over the weekend at least positively affects our body’s metabolism, which leads me to believe that maybe those extra hours could positively affect other bodily functions and mechanisms.
I next looked at this experiment, which studied 30 healthy young men and women for 13 nights, and what I was most interested to see was how sleep recovery affected their performance levels, as this is something that particularly applies to us as students. Four of those 13 nights allowed for eight hours of sleep, the next six were just six hours per night, and the final three nights—the recovery nights—were 10 hours per night. The researchers measured IL-6 and cortisol levels as well as used subjective and objective tests to record how sleepy the subjects felt. They found that after recovery sleep, sleepiness, fatigue, IL-6 levels and cortisol levels were corrected, but the lack in performance functioning was not. So it seems that the overall effects of a long-term pattern of sleep deprivation during the week and “catching-up” on the weekend are still not known, but from this small study it seems that performance levels are negatively affected whether we catch up on that sleep over the weekend or not, which is bad news for us.
A meta-analysis of 19 studies expanded on this conclusion and found that sleep deprivation overall impairs general functioning ability and that mood is the most affected by lack of sleep compared to cognitive or motor functioning. It was also found that partial sleep deprivation—a period of time in which one consistently gets less sleep than they need, affects functioning more than long-term or short-term sleep deprivation. This means that college students, who according to this recent study conducted by Jawbone receive on average 7.03 hours of sleep during the week, are in this category of partial sleep deprivation, the most detrimental kind of sleep deprivation. And according to this same study, the average amount of sleep that Penn State students get on a weekday night is just 6.94 hours, lower than the overall average. Upon first glance, it may seem that 6.94 hours of sleep is not too bad—it’s only a few minutes less than the recommended 7-9 hours per night, but remember, this number is just the average, meaning that a large majority of students are getting even less sleep than the recommended amount.
So it seems like catching up on sleep, although it may help a little bit, still doesn’t reverse many of the negative consequences that come from lack of sleep. But there are still ways for us to overcome our sleep debt.
The Harvard Medical School recommends that, if we aren’t getting enough sleep, we should add three to four hours of extra sleep over the weekend and an extra hour or two per night for the entire next week. But if getting that extra hour or two in per night doesn’t seem possible, perhaps take a cat-nap of around 20 minutes, as that has been found to equal one hour of extra sleep at night. And most importantly, focus on the long-term and work to reset that biological clock. Thanksgiving break would be a great time for this. Allow yourself to go to bed when you’re tired and wake up without an alarm clock every day. This will let your body find its natural rhythm, so that you can come back to school refreshed and ready to succeed!